徐玉兰是越剧小生流派“徐派”的创始人，她的艺术生涯可以追溯到十三岁时在浙江新昌的东安剧社开始学习。最初她掌握了花旦的技巧，然后转而学习文武老生的表演，唱功和武艺都有扎实的基础。在1941年12月，她决定专攻小生角色，并与施银花、赵瑞花、王杏花、筱丹桂等多位同行合作表演。她在1947年的剧目《是我错》中首次展现出独特的声音风格，而后成立了自己的剧团——玉兰剧团，这时候她的个人风格得到了进一步发展。

徐玉兰的唱腔特点是充满激情和热量，同时又兼具刚强和柔美。她拥有优质的声音，音色清脆明亮，音域宽广，常使用11度音区 hersinging style is characterized by its high-pitched and intense quality, with a wide range that often extends to 11 degrees. Her voice draws heavily from traditional "hantong" melodies in Shaoxing opera, as well as the soaring lines of Peking Opera. The contours of her voice are bold and distinct, with most of her melodies centered around middle-to-high notes. She has successfully broken free from the more subdued tones typical of Yueju opera, injecting a sense of grandeur and passion into her performances. Furthermore, she has also innovated in the use of lower registers, allowing for a wider range of emotional expression beyond mere sadness or pain.

In essence, Xu Yulan's singing style was revolutionary for its time - it was both exhilarating and moving at once - bringing new life to the art form while staying true to its roots.